JPH03121307A - Ceramics bearing - Google Patents

Abstract

PURPOSE:To smoothly support a radial load and a thrust load by forming cylindrical faces parallel to an axial core and faces approximately perpendicular to the axial core on an inner wheel and an outer wheel to constitute sliding contact faces. CONSTITUTION:A radial load is transmitted to an inner wheel 1 from a journal 3a as well as transmitted to an outer wheel 2 via cylindrical faces 1a, 2a, then transmitted from the outer wheel 2 to a mechanical frame 6 and supported by the mechanical frame 6. A thrust load is transmitted to the inner wheel 1 from a step 3b of a shaft 3 via a contact face 1c of the inner wheel 1 as well as transmitted to the outer wheel 2 via flat faces 1b, 2b and transmitted from a flat face 2e of the outer wheel 2 to the mechanical frame 6 and supported by the frame 6, By thus constituting the cylindrical faces 1a, 1a formed in parallel to an axial core 5 and the flat faces 1b, 2b formed approximately perpendicular to the axial core 5 as contact faces which are in sliding contact respectively, the shaft 3 to which the radial load and the thrust load simultaneously function can be smoothly supported.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a ceramic bearing capable of supporting a shaft on which a thrust load and a radial load act simultaneously or selectively.

<Prior Art> When a rotating shaft is attached to a machine frame or the like, it is common practice to use a sliding bearing or a rolling bearing.

The rolling bearing includes balls between the inner ring and the outer ring.
There are various types such as ball bearings, roller bearing links, and needle bearings that are equipped with transfer members such as rollers and needles.There are also types such as radial bearings and thrust bearings depending on the method of supporting the load acting on the shaft fitted to the inner ring. There is.

Also, deep groove bearings, angular bearings,
Taber roller bearings and the like are known as bearings that can support a shaft on which a radial load and a thrust load act simultaneously. Since many types of these rolling bearings are standardized, the most suitable one is selected and used when designing a machine.

The sliding bearings include those constructed by laminating a white metal layer on a support such as steel, cast iron, or copper, and those constructed by laminating or embedding an oil-impregnated alloy. There are also those made of gun metal 9 synthetic resin formed into a sleeve shape. 0 Normally, sliding bearings are standardized separately for bearings for supporting radial loads and bearings for supporting thrust loads. .

Each of the above-mentioned rolling bearings and sliding bearings has unique characteristics, and when using these bearings, the most suitable one is used in consideration of these characteristics.

On the other hand, recently, ceramics have been developed that have high compressive strength, wear resistance, and a low coefficient of friction.The applicant has developed several types of ceramic bearings and has already filed a patent application. 63-325933, etc.).

<Problems to be Solved by the Invention> The above-mentioned rolling bearings have problems such as flaking due to rolling fatigue, which inevitably leads to a fixed life span, low heat resistance, and high costs due to the large number of component parts. There is.

In addition, in the above-mentioned sliding bearing, the outer periphery of the shaft comes into sliding contact with the inner periphery of the bearing, resulting in large friction loss.For this reason, it is necessary to apply forced lubrication or self-lubrication to the contact surface between the shaft and the bearing. be. Furthermore, when a radial load and a thrust load act on the shaft simultaneously, there is a problem in that it is necessary to use a combination of commercially available radial bearings and thrust bearings, or to design a new bearing each time.

An object of the present invention is to provide a sliding bearing made of ceramics that can support a shaft on which a radial load and a thrust load act simultaneously.

Means for Solving the Problems> In order to solve the above problems, a ceramic bearing according to the present invention has a shaft hole formed in the center for fitting a shaft, and a shaft hole parallel to the axis of the shaft hole on the outer periphery. a ceramic inner ring having a cylindrical surface and a plane substantially perpendicular to the axis of the shaft hole at the end thereof; It is constructed by combining a ceramic outer ring formed with a flat surface connected to the cylindrical surface and slidingly in contact with a flat surface formed at the end of the ceramic inner ring.

According to the above means, the ceramic inner ring (hereinafter referred to as "inner ring")
A shaft hole for fitting the shaft is formed at the center of the inner ring, and a cylindrical surface parallel to the axis of the shaft hole is formed on the outer periphery of the inner ring, and a cylindrical surface is formed at the end approximately perpendicular to the axis of the shaft hole. Along with forming a plane,
A cylindrical surface is formed on the ceramic outer ring (hereinafter referred to as "outer ring J") to make sliding contact with the cylindrical surface formed on the outer periphery of the inner ring, and a flat surface that is connected to this cylindrical surface and makes sliding contact with the flat surface formed at the end of the inner ring is formed. Since the bearing is constructed by combining the inner ring and outer ring, when a shaft on which a radial load and a thrust load act simultaneously is fitted into the shaft hole of the inner ring, the cylindrical surface formed on the inner ring and outer ring In addition to supporting the radial load acting on the shaft, the flat surfaces formed on the inner and outer rings can support the thrust load acting on the shaft.

<Example> An example of a bearing to which the above means is applied will be described below with reference to the drawings.

FIG. 1 is an explanatory developed view of the bearing according to the present invention, and FIG. 2 is an explanatory view of the bearing in use.

In the figure, a bearing A is constructed by combining an inner ring 1 and an outer ring 2.

The inner ring is formed by filling a mold with an oxide ceramic raw material such as alumina or PSZ, press-forming the mold, and firing the molded product at about 1500°C to 1600°C.

A shaft hole 4 into which a shaft 3 is fitted is formed at the center of the inner ring l. The shaft hole 4 is formed with a predetermined fitting tolerance depending on the diameter of the shaft 3 to be fitted into the shaft hole 4.

The shaft hole 4 is formed at the same time as the inner ring 1 is formed.

Note that 5 is the axis of the shaft hole 4, which is the same as the axis of the bearing A.

A cylindrical surface 1a is formed on the outer periphery of the inner ring 1 in parallel to the axis 5. The cylindrical surface 1a is in sliding contact with a cylindrical surface 2a formed on an outer ring 2, which will be described later, and transmits the radial load acting on the shaft 3 to the outer ring 2. For this reason, the cylindrical surface 1a needs to be exactly parallel to the axis 5. Further, the diameter of the cylindrical surface 1a is set to a size that allows the inner ring 1 to have sufficient rigidity according to the value of the radial load that the bearing A should support, and the length of the inner ring 1 is similarly set to a value that allows the inner ring 1 to have sufficient rigidity. is set according to the value of the thrust load to be supported.

A plane 1b substantially perpendicular to the axis 5 is formed on one end surface of the inner ring 1. The plane 1b is a plane 2 formed on the outer ring 2.
The thrust load acting on the shaft 3 through sliding contact with the outer ring 2
It is intended to be communicated to the public. In addition, the other end surface of the inner ring 1 is the shaft 3.
The abutment surface IC on which the stepped portion 3b of the journal portion 3a abuts is formed in a plane perpendicular to the axis 5, similar to the plane 1b.

The outer ring 2, like the inner ring 1, is formed by filling a mold with an oxide ceramic raw material such as alumina or PSZ, press-molding the material, and firing it at about 1500°C to 1600°C.

Inside the outer ring 2, there is a cylindrical surface 1a formed on the outer periphery of the inner ring 1.
A cylindrical surface 2a is formed with a predetermined tolerance. The cylindrical surface 2a is in sliding contact with the cylindrical surface 1a of the inner ring 1, and the radial load acting on the shaft 3 transmitted through the inner ring 1 is transmitted thereto. Therefore, the cylindrical surface 2a is constituted by a surface parallel to the axis 5.

Inside the outer ring 2, there is a plane 2b connected to the cylindrical surface 2a and extending in a direction substantially perpendicular to the cylindrical surface 2a, that is, substantially perpendicular to the axis 5.
is formed. This plane 2b is in sliding contact with a plane 1b formed on the inner ring 1, and is used to transmit the last load acting on the shaft 3 through the inner ring 1.

A hole 2C is formed in the center of the outer ring 2 and connected to the plane 2b. The hole 2C is formed to have a diameter that allows the shaft 3 fitted into the shaft hole 4 of the inner ring 1 to be loosely fitted therein.

The outer circumference 2d of the outer ring 2 is formed into a cylindrical shape parallel to the axis 5. Further, an end surface 2e of the outer ring 2 on the hole 2C side is configured as a plane formed perpendicular to the axis 5. The outer periphery 2d and the plane 2e form a machine frame 6, which will be described later in the bearing A.
Alternatively, it serves as a fitting portion when attached to a casing or the like (not shown).

The shaft hole 42 in the inner ring 1 has a cylindrical surface 1a and a thousand-face 1b, and the outer ring 2 has a cylindrical surface 2a and a flat surface 2b.

The hole 2c, the outer circumference 2d, and the end surface 2e are the inner ring! , are formed simultaneously when the outer ring 2 is press-molded.

In the above molding, the inner ring 1. The dimensional accuracy for the outer ring 2 can be about ±0.005 vr of the set dimensions of each part, and the surface roughness can be about RAo of about 8.

In order to configure a bearing with the inner ring 1 and outer ring 2 configured as described above, the cylindrical surface 1a of the inner ring 1 and The plane 1b is fitted. This makes it possible to support the shaft 3 that fits into the inner ring 1 by bringing the cylindrical surfaces 1a, 'la and the flat surfaces 1b, 2b into sliding contact, respectively.

After fitting the inner ring 1 to the outer ring 2, it is preferable to wrap the respective contact surfaces constituted by the cylindrical surfaces 2a, 1a and the flat surfaces 2b, 1b.

This lapping can be carried out by applying an abrasive such as diamond powder to each of the contact surfaces and by applying relative rotation between the inner ring 1 and the outer ring 2. By lapping the outer ring 2 and the inner ring 1, it becomes possible to rotate the bearing A more smoothly.

In addition, the cylindrical surface 1a of the inner ring 1 and the outer ring 2 constituting the bearing A
It is also possible to polish the surfaces such as the cylindrical surface 2a and the outer periphery 2d according to the accuracy required for the bearing A.

A case in which the shaft 3 is supported by the bearing A configured as described above will be explained with reference to FIG.

In the figure, the outer ring 2 constituting the bearing A is the machine frame 6.
is non-rotatably mounted. Further, the journal portion 3a of the shaft 3 is fitted into the shaft hole 4 of the inner ring 1, and the stepped portion 3b of the shaft 3 is brought into contact with the contact surface IC of the inner ring l.

Here, assuming that a radial load in the direction of the arrow a and a thrust load in the direction of the arrow are acting on the shaft 3 at the same time, the radial load is transmitted from the journal portion 3a to the inner ring 1 and the cylindrical surface 1a.

It is transmitted to the outer ring 2 via 2a. Furthermore, it is transmitted from the outer ring 2 to the machine frame 6 and supported by the machine frame 6. Further, the thrust load is transmitted from the stepped portion 3b of the shaft 3 to the inner ring 1 via the contact surface IC of the inner ring 1, and
It is transmitted to the outer ring 2 via the planes 1b and 2b. Furthermore, it is transmitted from the plane 2b of the outer ring 2 to the machine frame 6 and is supported by the machine frame 6.

As described above, in the bearing according to the present invention, the cylindrical surfaces 1a and 2a formed parallel to the axis 5 and the flat surfaces 1b and 2b formed substantially perpendicular to the axis 5 are brought into sliding contact, respectively. By configuring it as a contact surface, it is possible to smoothly support the shaft 3 on which a radial load and a thrust load act simultaneously.

In the bearing A, the dimensions of the inner ring 1, that is, the cylindrical surface 1a
It is possible to set the diameter and length of the shaft 3 according to the values of the radial load and thrust load acting on the shaft 3. Therefore,
When the radial load acting on the shaft 3 is large, the inner ring 1
By increasing the diameter of the inner ring 1, it is possible to increase the rigidity of the inner ring 1.

However, if the diameter of the inner ring 1 is made thicker, the flat surface 1b.

The contact area of the contact surface 2b becomes large, and therefore, the circumferential speed of the contact surface varies depending on the radial position of the contact surface, resulting in a large friction loss. In order to reduce the friction loss, the cylindrical surface 1a and the flat surface 1b of the inner ring 1 are
It is preferable to form a chamfered portion 1d having relatively large dimensions as shown in FIG. 3 on the ridge line where the two are connected.

In this way, by forming the chamfered portion 1d on the inner ring l, the rigidity of the inner ring 1 is increased and the cylindrical surfaces 1a and 2a are
And it becomes possible to reduce the contact area between the planes 1b and 2b. That is, by reducing the area on which the radial load and thrust load act, it is possible to reduce the friction loss, especially on the planes 1b and 2b.

As mentioned above, the cylindrical surfaces 1a, 2a and the flat surface 1b.

By reducing the contact area of the inner ring 1.2b, the surface pressure on the contact surface increases. Since the outer ring 2 is made of ceramics, it has sufficient pressure resistance.

Furthermore, by forming the chamfered portion 1d on the inner ring 1, the inner ring 1 can be smoothly fitted into the recess formed by the cylindrical surface 2a formed on the outer ring 2 and the flat surface 2b continuous with the cylindrical surface 2a. be.

In the inner ring 1, a step having a minute height is formed on the surface opposite to the plane 1b, and the surface of the contact surface is the contact surface 1.
It is configured as e. Further, the contact surface 1e is formed as a surface perpendicular to the axis 5. By configuring the contact surface 1e as described above, it is possible to improve the perpendicular accuracy of the cough surface 1e with respect to the axis 5. Furthermore, by forming the contact portion 1e on the inner ring 1, when the journal portion 3a of the shaft 3 is fitted into the shaft hole 4 of the inner ring 1 and the step portion 3b is brought into contact with the contact portion 1e, the step portion There is no risk that 3b will come into contact with the outer ring 2.

In the bearing A, since the inner ring 1 and the outer ring 2 are each made of ceramic, the friction coefficient is small and the loss due to friction is small. Therefore, when supporting the shaft 3, there is no need to lubricate the contact surfaces of the cylindrical surfaces 1a, 2a and the flat surfaces 1b, 2b. Furthermore, even when heat is generated due to sliding friction, the coefficient of thermal expansion of ceramics is approximately 8 to 11.
Since it is about X 10-b/'C, the inner ring 1. Excessive thermal stress due to thermal expansion of the outer ring 2 does not occur.

Furthermore, the heat resistance temperature of ceramics is approximately 00℃~1000℃.
℃, the heat generation causes the inner ring 1. Outer ring 2
There is no risk of deterioration.

<Effects of the Invention> As explained in detail above, the ceramic bearing according to the present invention has a cylindrical surface parallel to the axis in the inner ring and an outer ring, and a plane substantially perpendicular to the axis. By configuring the surface as a sliding contact surface, even if a radial load and a thrust load act simultaneously on the shaft fitted to the inner ring, the radial load and thrust load can be supported smoothly.

Furthermore, since the bearing can be configured with two members, the inner ring and the outer ring, the number of parts can be reduced and the cost of the bearing can be reduced.

In addition, since the shaft can be supported by sliding contact between the inner ring and the outer ring, there is no relative slippage between the inner ring and the shaft.Therefore, there is no risk of the shaft wearing out, and the shaft has a long lifespan. can be made longer.

Furthermore, since the inner ring and outer ring are molded from ceramics, the coefficient of friction at the sliding contact surfaces is small.Therefore, less heat is generated due to friction, and special lubrication of the contact surfaces is not required. Therefore, 1. It is possible to construct a bearing that is easy to maintain.

Furthermore, since the coefficient of thermal expansion of ceramics is small, even if the bearing generates heat, there is no risk of thermal effects on the shaft, machine frame, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory developed view of the bearing according to the present invention, FIG. 2 is an explanatory view of the bearing in use, and FIG. 3 is an explanatory view of another embodiment of the inner ring. A is the bearing, 1 is the inner ring, 2 is the outer ring, la and 2a are the cylindrical surfaces,
lb, 2b are flat surfaces, IC is a contact surface, 1d is a chamfered part, 2
d is the outer circumference, 3 is the shaft, 3a is the journal part, 3b is the stepped part,
4 is a shaft hole, and 5 is a shaft center. Figure 3 Figure 1

Claims (1)

[Claims] A ceramic material having a shaft hole in the center for fitting a shaft, a cylindrical surface parallel to the axis of the shaft hole on the outer periphery, and a plane substantially perpendicular to the axis of the shaft hole at the end. A cylindrical surface is formed on the inner periphery of the inner ring made of ceramic, and the cylindrical surface is in sliding contact with the cylindrical surface formed on the outer periphery of the inner ring made of ceramics, and the cylindrical surface is connected to the cylindrical surface and comes into sliding contact with the flat surface formed on the end of the inner ring made of ceramics. A ceramic bearing characterized by being constructed by combining a flat ceramic outer ring.